System and method for on-line mixing and application of surface coating compositions for food products

ABSTRACT

A process and apparatus for preparing a surface coating composition for an animal food. The process involves combining, in-line along a food processing line, liquid fat and a dry additive to provide a liquid fat-dry additive composition, which then is combined with a liquid additive to provide a surface coating composition. The composition is coated on the food.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.10/200,556, filed Jul. 22, 2002, now U.S. Pat. No. 7,479,294, whichclaims the benefit of priority to U.S. Provisional Patent ApplicationSer. No. 60/307,229, filed Jul. 23, 2001, which is hereby incorporatedby reference.

FIELD OF THE INVENTION

The invention provides a process for preparing and applying a surfacecoating composition for food such as animal food having dry and liquidadditives.

BACKGROUND OF THE INVENTION

In the pet food industry, palatability enhancing materials, oftenreferred to as “palatants,” may be provided to certain foods categorizedgenerally as “kibble,” to increase enjoyment of the food while providingfor the nutritional needs of the animal. As used in this industry,“palatability” generally encompasses within its meaning all of thevarious properties of the food that can be sensed by an animal,including taste and smell. Materials such as animal origin digests,organic acids and their salts, and different types of meat proteins arecommonly used to enhance the palatability of the pet foods. These may beeither liquid or dry, depending on the desired properties. It is alsodesirable to increase other properties of the animal food whilemaintaining its palatability. Therefore, functional additives, such asprobiotic microorganisms, vitamins, certain pharmaceutical compounds,and tartar control agents, may be provided in animal food to increasethe overall benefit to the animal. Palatants and other functionaladditives can either be incorporated into the food or can be topicallyapplied onto the surface of the food. Surface application is commonlydone following extrusion of the food product. Surface application isgenerally preferred as a method of providing these additives, becauseeither the flavor of the additive, such as a palatant, can be masked byother ingredients within the kibble, or the additives may lose theirdesired properties through process-sensitive decomposition if they areincorporated into (i.e., intermixed with) the food composition itself.Further more, it is known that some additives, such as tartar controlagents, may be made more immediately available at a higher concentrationin the oral cavity if provided on the surface of the animal food. It istherefore often preferred in the art to surface coat the animal foodwith the palatants and other beneficial additives.

In general, application of materials to the surface of the food isusually performed using a staged application or other types ofprocesses. With respect to the staged surface coating process, it iscommon in the art to apply liquid fat to the surface of the animal food,followed by the application of dry and liquid additives. In the stagedapplication process, the liquid fat is generally used as a binder tosecure the dry and liquid additives to the surface of the animal food.To utilize the fat as a binder in staged application, however, dry andliquid additives generally must be applied in excess to ensure that theanimal food is sufficiently coated with the additives, and a significantamount of the excess additives may be wasted, thereby contributing toincreased costs of production, raw material, storage, and clean-up.Furthermore, it may be difficult to optimize or change the amounts ofdry and liquid additives applied to the surface of the animal food whenchanging from one product to another without having to first shut downthe entire staged application process. When changing the mixes fordifferent product runs, entire batches of liquid-dry mixes must beremoved and exchanged.

To overcome some of the problems associated with the staged applicationprocess, a simultaneous application process is often employed asalternative. In the simultaneous application process, liquid fat is usedas a carrier and binder substrate for the dry and liquid additives.Specifically, liquid fat, dry additives, and liquid additives are mixedsimultaneously to form a surface coating composition. Other approachesresult in highly viscous compositions, which can be more difficult toprovide the ingredients to the surface of the food in a uniform manner.Furthermore, many of the dry materials contained in the surface coatingcomposition, such as, for example, vitamins, antioxidants, probioticmicroorganisms, pharmaceuticals, enzymes, peptides, proteins, herbals,flavors, and the like, may more likely be degraded during mixing whenall additives are combined well before application, thereby increasingthe exposure of certain ingredients to process and environmentalconditions such as moisture, acidic components within a prepared digest,heat, shear or pressure, or a combination of two or more of these orother deleterious factors. Specifically, the liquid additives, which arelikely aqueous and highly acidic, may subject dry additives tohygroscopic effects such pH change or water activity due to exposure towater during mixing, causing a loss of desired efficacy of the dryadditives.

Therefore, there exists a need in the art for a process of surfacecoating animal food with dry and liquid additives that overcomes theaforementioned problems.

SUMMARY OF THE INVENTION

A system and method are provided for preparing a surface coatingcomposition for a food product, particularly an animal food product.Specifically, the method provides a modular, on-line mixing system thatallows ingredients to be mixed as needed, thereby reducing waste andviscosity build within the system. The process includes providing one ormore liquid fats, one or more dry additives, and one or more liquidadditives for application in an on-line application process whichresults in less decomposition or loss of desired ingredients and adecreased occurrence of formation of viscous solution which may impairthe application process and decrease uniformity of application.

In the on-line application process, use of metered mixing of componentsas needed minimizes reaction time for viscosity build, providing betteruniformity of application. In one embodiment, a liquid fat and a dryadditive are combined to provide a liquid fat-dry additive composition.The liquid fat-dry additive composition can then be combined with theliquid additive (to which a soluble liquid or dry additive may or maynot have been added) to provide a surface coating composition forapplication to a food product following extrusion and drying. “Dryadditive” is meant to include at least one dry additive. Similarly, “aliquid additive” is meant to include at least one liquid additive.

In another embodiment, the method includes mixing of less stableingredients into the appropriate carrier, such as fat or oil, to provideprotection from additional ingredients which must be added to thesurface of the food. Mixing is done essentially at the point ofdelivery, minimizing exposure to deleterious environmental elements.On-line delivery and mixing of ingredients allows combinations ofsuitable carriers with specific ingredients without necessitatingshut-down of the processing operation to provide for mixing as newingredients are needed.

Further, a method is provided for protecting the stability of a dryadditive from, for example, moisture, hygroscopicity, and pH change whenexposed to a liquid digest formed of components of animal origin, orother artificially or naturally occurring environmental influences.Specifically, the method includes encapsulating a dry additive in aliquid fat to provide fat-encapsulated dry additive. Such methodprovides for the stability of the dry additives which are protected frommoisture, hygroscopicity, and pH change by the fat when exposed to theliquid animal digest.

The inventive process overcomes the shortcomings associated with stagedapplication of dry and liquid additives onto the surface of animal food.The process allows for optimizing the amount of dry additives on thesurface of the animal food while minimizing waste. Also, the process ofsurrounding or encapsulating dry additives in liquid fat prior to theaddition of liquid additives protects unstable and sensitive additivesduring the production of a surface coating composition, while minimizingthe time for viscosity to build before application. Furthermore, theon-line mixing and application provided by the present invention gives asignificant benefit by providing for more uniform application of surfacecoating compositions and essentially eliminating costly delays andrepairs caused by formation of viscosity in mixed compositions astraditionally used in either simultaneous or staged applicationprocesses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of the overall system and method.

FIG. 2 is a schematic representation of one embodiment of the system andmethod.

DETAILED DESCRIPTION OF THE INVENTION

A system and method for on-line mixing and application of a surfacecoating for foods using a combination of ingredients are providedherein. The inventors have developed a novel system and method foron-line application of combinations of dry additives, liquid (aqueous)additives, and fat additives which allows additives to be mixed asneeded, minimizing reaction time between ingredients within the systemfor viscosity build and providing a more uniform application. Mixing isdone as ingredients are needed for delivery into the system forapplication, and application is performed after extrusion and drying.The on-line mixing system allows ingredients which are more sensitive tophysical and chemical elements within the system to be protected bymixing them into an appropriate carrier to provide a protective coating(such as coating in fat or oil, for example), and decreasingdecomposition due to shear, pressure, heat, or other factors by mixingand applying post-extrusion and post-drying. In one embodiment, aprocess is provided for surface coating animal food with a dry additivethat is either sensitive to or unstable in the presence of a liquidadditive. The process includes mixing liquid fat and the dry additive ina dry mix module to form a liquid fat-dry additive composition. Theliquid fat-dry additive composition is then mixed with the liquidadditive, e.g., liquid digest, in a liquid mix module to form thesurface coating composition. The surface of the animal food is thencoated with the surface coating composition from the liquid mix module,thereby providing a coated animal food.

Unstable or sensitive, as used herein, refers to the loss or potentialloss of efficacy of an additive, i.e., loss of palatability or nutritivevalue, caused by the presence of another additive, process conditions orenvironmental conditions, regardless of whether the loss of efficacy isdue to a chemical, physical or biological change.

The food product can be any suitable composition that is ingestible by ahuman or an animal and that provides nutritional value to the human oranimal. The food can be coated or uncoated prior to being treated inaccordance with the invention. An animal food generally will be a basalfood composition having a nutritionally balanced mixture ofproteinaceous and farinaceous ingredients, which have a moisture levelof less than about 50% by weight. The food product can be baked,extruded, pelleted, or formed. Such forms of food products, and methodsfor their production, are well known to those of skill in the art offood manufacturing. Extrusion and extrusion cooking, for example, aredescribed on pages 794-800 of the Encyclopedia of Food Science andTechnology, Volume 2 (Y. H. Hui, ed., John Wiley & Sons, Inc. 1992).

The embodiment provides a method for mixing and applying a coatingcomposition for a variety of types of foods. The method can be used, forexample, to provide a vitamin coating for breakfast cereal, a coating oftartar control agents on cereal treats and coated snack foods, or acoating of vitamins, flavorings, or other additives for potato chips orcheese curls.

Generally, aside from the nutritional balancing additives included inthese products, such as the vitamins and minerals, or the otheradditives, such as preservatives and emulsifiers and the like, theanimal food for the most part will consist of ingredients which may bedescribed as substantially proteinaceous or substantially farinaceous.Although the following should not be considered limiting, aproteinaceous ingredient can generally be defined as any material havinga protein content of at least about 15% by weight, whereas a farinaceousmaterial has a protein content substantially below this and has a majorfraction of starchy or carbohydrate containing materials.

Examples of proteinaceous materials, which are typically used incommercial animal foods, are vegetable protein meals, such as soybean,cottonseed, peanut, animal proteins such as casein, albumin, and meattissue including fresh meat a well as rendered or dried “meals” such asfish meal, poultry meal, meat meal, meat and bone meal,enzymatically-treated protein hydrolysates, and the like. Other types ofproteinaceous materials include microbial protein such as yeast, andother types of protein, including materials such as wheat gluten or corngluten.

Examples of typical farinaceous materials include enzymatic farinaceousmaterials, grains such as corn, maize, alfalfa, wheat, soy, sorghum,barley, and various other grains which are relatively low in protein.Numerous other materials could be added to the animal food, especiallycat food, which do not necessarily fall into either category, such asdried whey, and other dairy by-products or carbohydrates.

The animal food is not limited to a particular composition. In general,however, the term “animal food” is intended to apply to nutritionallybalanced animal food products, such as, for example, commerciallyavailable dog and cat food and treats. The animal food meeting thisdefinition can be characterized as having minimum nutrient levels knownto those of skill in the art. Preferred animal foods are those that arenutritionally balanced. The animal food can be any suitable form and istypically in bite-size or pellet form of any shape.

The term “fat” refers to any edible grade fat or lipid, including fatsof avian, animal, plant, or manufactured origin, including, but notlimited to, crude or refined fats. Typical animal origin fats include,for example, animal tallow, choice white grease, lard, milk-derived fatssuch as butter oil, and fat typically contained in cheese. Typical fatsof vegetable origin include coconut oil, soybean oil, and corn oil.Typical fats of avian origin include fats derived from the tissue ofchickens, turkeys, ducks, and geese, for example.

The term “liquid fat” refers to fat that is substantially flowable,i.e., liquid. The fat can be liquid at room temperature or renderedsubstantially flowable by heating the fat until the desired flowabilityis achieved. Preferably, the fat is substantially flowable attemperature between about 10° C. to about 90° C.

The term “dry additive” refers to an additive that is solid at about 25°C. and has a moisture content below about 35 wt %. Typical dry additivesinclude, for example, meat solids, dry animal digest, dry palatants,antibiotics, protiotics, protiotic microorganisms, vitamins, minerals,and tartar control agents.

Meat solids refers to meat and meat by-product. Meat is the tissue of ananimal, such as the flesh of cattle, swine, sheep, goats, and othermammals. The meat preferably is beef, veal, or pork. Other sources ofsolids and by-products include tissue derived from chicken, turkey,duck, goose, or fish. “By-product” is the non-rendered part of a carcassof a slaughtered animal, including a mammal, bird, or fish. The terms“meat” and “meat by-product” are used herein in the same manner asdescribed in the Definitions of Feed Ingredients published by theAssociation of American Feed Control Officials, Inc. (AAFCO).

Dry animal digest refers to a dry digest of meat solids (either meat ormeat by-product). Typically, a dry animal digest is prepared bysubjecting a meat by-product to proteolytic or lipolytic enzymedigestion, as is well known in the art, with reaction conditionspreferably controlled to obtain maximum flavor development. The productis typically then reduced to a substantially dry form, i.e., having lowmoisture content, to form the dry digest.

Dry palatants refer to any dry additives that increase the palatabilityof food to an animal. As such, palatants typically include meat andcheese flavorings and, therefore, can include meat solids and dry animaldigest, but also include other components that can be present as dryadditives, such as herbs, flavors, and the like. Examples of drypalatants include Brewer's yeast, which comprises dried pulverized cellsof a yeast of the genus Saccharomyces (usually S. cerevisiae), oftenused in brewing, Torula yeast, and various yeast extracts. It is knownto those of skill in the art that a variety of yeasts can be used aspalatants.

The dry additives can include any suitable antibiotics, prebiotics,probiotics, 5 and vitamins. Suitable probiotic microorganisms caninclude yeast such as Saccharomyces, Debaromyces, Candida, Pichisa andTorulopsis, molds such as Aspergillus, Rhizopus, Mucor, and Penicilliumand bacteria such as the genera Bifidobacterium, Bacteroides,Clostribium, Fusobacterium, Melissococcus, Propionibacterium,Streptococcus, Enterococcus, Lactococcus, Staphylococcus,Peptrostrepococcus, Bacillus, Pedicoccus, Micrococcus, Leuconostoc,Weissella, Aerococcus, Oenococcus and Lactobacillus. Specific examplesof suitable probiotic microorganisms are: Saccharomyces cerevisiae,Bacillus coagulans, Bacillus licheniformis, Bacillus subtilis,Bifidobacterium bifidum, Bifidobacterium infantis, Bifidobacteriumlongum, Enterococcus faecium, Enterococcus faecalis, Lactobacillusacidophilus, Lactobacillus alimentarius, Lactobacillus casei subsp.Casei, Lactobacillus casei Shirota, Lactobacillus curvatus,Lactobacillus delbruckii subsp. Lactis, Lactobacillus fareciminus,Lactobacillus gasseri, Lactobacillus helveticus, Lactobacillusjohnsonii, Lactobacillus reuteri, Lactobacillus rhamnosus (LactobacillusGG), Lactobacillus sake, Lactococcus lactis, Micrococcus varians,Pediococcus acidilactici, Pediococcus pentosaceus, Pediococcusacidilactici, Pediococcus halophilus, Strepococcus faecalis,Streptococcus thermophilus, Staphylococcus carnosus, and Staphylococcusxylosus. The probiotic microorganisms preferably are in powdered, driedform. Those microorganisms are encapsulated, for example, in liquid fat,using the method of the present invention, to increase the likelihood oftheir survival on the animal food until digestion by an animal.

Other dry additives can include, for example, antioxidants, carotenoids,lutein, bioflavonoids, vitamins, minerals, natural or organicfermentation products or extracts, enzymes, microbial growth inhibitors,and compounds which can provide a benefit by decreasing oral malodor.

Dental active agents are any agents that act to inhibit or preventdental calculus (tartar) and plaque build-up on the teeth of animals.Suitable tartar control agents include, but are not limited to, crystalgrowth inhibitors, such as soluble pyrophosphates, sodiumtripolyphosphate, sodaphos, sodium acid metaphosphate, solublediphosphonates, and certain soluble zinc compounds, such as zincchloride, and sequestrants, such as sodium hexametaphosphate,hydroxycarboxylic acids, including citric acid, fumaric acid, glutaricacid, acetic acid, oxalic acid, and the like, and their alkali salts,such as sodium citrate, potassium citrate, etc., as well as theiraminopolycarboxylic acid derivatives, such as, for example,ethylenediaminetetraacetic acid. Other suitable tartar control agentsmay include microbial growth inhibitors and enzymes, particularlyenzymes that can act by inhibiting deposition of calculus or by breakingdown formations of calculus within the oral cavity. Cyclodextrins orother odor control or odor modoulating compositions can also be used incoating compositions for application in the method of the presentinvention.

The dry additives can include other components, such as food gradepigments, viscosity modifiers, pH adjusters, and the like, to desirablyaffect the surface coating composition and/or the animal food to whichit is applied.

The term “liquid additive” refers to an additive that is substantiallyliquid at 25° C. or a substance that has a moisture content above about35 wt. %. Suitable liquid additives include, for example, water,non-aqueous liquids, aqueous and non-aqueous liquid systems (includingliquid emulsions), fat-miscible and immiscible liquids, and suspensionsor dispersions of solids in liquids. Typical liquid additives includeliquid animal digest, oil, water, vitamins, amino acids, proteins,nutrients, oils, flavors, acidulents, food grade dye compositions, andcolorants (such as caramel, which also provides flavor). Liquid animaldigest is similar to its dry counterpart, discussed above, except thatit is fluid or can be made flowable when applied.

The surface coating composition comprises liquid fat, dry additives, andliquid additives, or any combination thereof, in any suitable amounts.The surface coating composition typically comprises about 1 to about9.95 wt. % (optionally, about 35 to about 99.95 wt. %) liquid fat, about0 to about 60 wt. % (optionally, about 1 to about 50 wt. %) dryadditives, and 0 to about 99.95 wt. % (optionally, about 0 to about 80wt %) liquid additives.

Surface coating, as used herein, refers to the topical deposition of thesurface coating composition onto the animal food, such as by spraying,dipping, emulsifying, and the like. In one option, the surface coatingcomposition is coated onto the animal food uniformly or that uniformdistribution of the surface coating composition is achieved. One methodis repeated tumbling of the animal food in the presence of the coatingcomposition. One or more coats of the coating composition may be appliedto the animal food in accordance with the inventive method.

While the various palatability enhancers and nutritional additivesprovide a balanced diet for the consuming animal, they may also providesignificant processing problems when such additives are sensitive toprocessing and environmental conditions, and many of the dry additives,e.g., probiotic micro-organisms and tartar control agents, are unstablein the presence of aqueous and highly acidic environments. Inparticular, the dry additives of the preferred surface coatingcomposition are highly sensitive to moisture, hygroscopicity, pH change,and other processing and environmental considerations such as heat andmechanical shear. The liquid digest alone creates many of theseundesirable conditions, i.e., moisture, pH, etc., to the extent that thedry additives lose much their desired efficacy upon exposure to theliquid digest.

The inventive process overcomes the shortcomings associated with stagedand simultaneous application of dry and liquid additives onto thesurface of animal food. For instance, by surrounding or encapsulatingdry additives in liquid fat prior to the addition of liquid additives,the inventive process protects unstable and sensitive materials duringthe production of a surface coating composition. For example, probioticmicro-organisms (“probiotics”) may be added to the surface of animalfoods as a nutritive supplement. Probiotics are in a dormant state whendry. Encapsulating the probiotic micro-organisms in the liquid fatprotects them from moisture and nutrients, e.g., liquid digest.

It has been discovered that suspending probiotics in liquid digestactivates the micro-organisms such that they are no longer dormant. Whenthe probiotic micro-organisms are no longer dormant, they can growprematurely in the liquid digest and not in the intestines of theanimal. The premature growth of the micro-organisms contributes to aloss in efficacy. In fact, most of the probiotic micro-organisms aredestroyed before they ever reach the intestines of the animal unlessthey are first encapsulated in fat.

Probiotics are not the only unstable or sensitive dry additives. Otherdry additives are unstable under or sensitive to processing andenvironmental conditions, including exposure to the liquid digest. Forexample, many of the components of the surface coating composition aresensitive to moisture, heat, mechanical shear, pH, etc. Some examples ofmaterials preferably coated onto the surface of the animal food that aresensitive to or unstable under processing and environmental conditionsinclude vitamins, antioxidants, pharmaceuticals, enzymes, proteins,phosphates, herbals, and flavors, to name a few.

It has also been discovered that the high acid coating contributessignificantly to the loss of efficacy of the dry additives that aresensitive to acidic conditions or pH change. For example, it has beendiscovered that phosphates, probiotics, enzymes, dry palatants, etc.lose much of their desired properties unless they are first encapsulatedwith fat. The fat encapsulation protects the dry additives from the highacid liquid composition of the liquid digest and the surface coatingcomposition ultimately applied to the surface of the animal food.Accordingly, it has been discovered that encapsulating the dry additiveswith fat prior to the addition of destructive liquid additives, namelyliquid digest, substantially protects the palatability and/ornutritional value of the dry additives during the process ofmanufacturing animal food surface coated with dry and liquid additives.

The animal food may be produced in many different ways as desired. Petfoods, for example, are often produced by extrusion cooking. The driedfood pieces are introduced into a surface coating apparatus. The surfacecoating composition may be applied to the surface of the dried foodpieces by any appropriate method, such as spraying, mixing, or dippingthe food pieces with the surface coating composition to provide thedesired level of fat, dry additives, and liquid additives on the driedfood pieces. Preferably, the surface coating composition is introducedto an enrober with the dried food pieces. Although the type of equipmentused to facilitate the surface coating of the dried food pieces is notlimiting to the inventive process, suitable enrobing devices includedisk enrobing machines manufactured by Wenger (Sabetha, Kans.). Theenrobing procedure may be repeated to add multiple layers of the surfacecoating composition if desired.

Following the surface coating of the dried food pieces, the coatedpieces are collected and then transported, if desired, to a tumblingdrum or similar apparatus where the coated food pieces are tumbledrepeatedly to improve the uniformity of the coating. The surface coatedanimal food may be re-introduced to the enrober for additionalapplications of the surface coating composition. Once the tumblingprocess is completed, the surface coated food pieces can be removed fromthe tumbling drum and cooled to room temperature. The surface coatedanimal food is then ready for packaging and delivery.

A process is provided for surface coating animal food with dry andliquid additives resulting in a food product for animals having thedesired nutritional value and palatability. As is shown generally inFIG. 1, the process comprises mixing of additives from a dry materialhandling system (2) which is provided as needed by use of a drymaterials metering system (4) to a dry-liquid mix module (6), where thedry material is combined with liquid fat container (8). Once the drymaterial has been sufficiently mixed and coated with liquid fat, theentire mixture is transported to a liquid material has been sufficientlymixed and coated with liquid fat, the entire mixture is transported to aliquid-liquid mixing system (10), where one or more liquid additives(12, 14, 16) are provided for admixing with the dry-liquid fat mixture.

One embodiment for use in coating pet food kibble is shown generally inFIG. 2. As is shown in the schematic diagram of FIG. 2, a bulk bag (2)provides solids in-line to the food processing line. Solids from thebulk bag are fed into a surge bin (4) for handling the dry material andintroducing it into the mixing system. The surge bin preferably isfitted with high bin and low bin indicators to meter the flow of drymaterial into the system. From the surge bin (4), dry material istransported to a loss-in-weight, or weight-loss-differential, feeder(Acrison, Inc., Moonachie, N.J.), which meters the desired quantities ofdry material in-line into a medium/high shear mixer (IKA Works, Inc.,Wilmington, N.C., Model MHD5 or MDH10) along a food processing line.Other suitable dry-liquid mixing modules include, for example, thosemanufactured by Bematek Systems, Inc. (Beverly, Mass.) and Ross(Hauppauge, N.Y.).

Once in the medium/high shear mixer, the dry additives are combined withliquid fat from a liquid fat bin (10) or liquid fat source, which issupplied to the mixer through a metering system (12) in-line along thefood processing line. The admixed dry material and liquid fat are thentransported through a positive displacement pump (a variable speedcentrifugal pump controlled by inlet pressure), which pumps the mixtureto the mixing manifold (16) that is communicatively coupled with thefood processing line. The dry-liquid fat mixture is further combinedwith one or more liquids, such as liquid digest (18), a second majorliquid additive (20), and/or a minor liquid additive (28), each of whichis transported to the mixing manifold (16) through a metering system(22,24,30, respectively) for metering the appropriate amount of liquidadditive in-line into the food processing line. Once the dry-liquid fatmixture is combined with the one or more liquids, the mixture istransported in-line along the food processing line to a high shear mixer(Silverson Machines, Inc., East Longmeadow, Mass., Model L150 or L200),or a liquid-liquid mixer, communicatively coupled therewith. Thedry-liquid fat mixture can be thoroughly admixed with the one or moreliquid additives for application to the food product in the disk enrober(32) (Wenger, Sabetha, Kans.). In one option, the mixing manifold andhigh shear mixer are positioned near the enrober, to decrease thepotential for viscosity build in the system prior to application. Theenrober, to decrease the potential for viscosity build in the systemprior to application. The enrober, in one option, is positioned at asecond end of a food processing line, and the liquid-liquid mixer ispositioned in close proximity to the enrober.

The dry additives, such as, for example, dry digest, dry meat,probiotics, tartar control additives, yeast, vitamins, pharmaceuticals,and the like, at ambient temperatures are mixed with the liquid fat. Theresidence time of the dry additives mixed with the liquid fat isdependent upon the formulation of the surface coating composition, aswell as process considerations, such as the choice of equipment. Many ofthe dry additives are unstable in the presence of the liquid additives,e.g., liquid digest. The residence time of the dry additives mixing withthe liquid fat is sufficient to ensure that the dry additives aresuspended thoroughly in the liquid fat in order to protect them from theliquid additives mixed with the liquid fat-dry additive composition inthe liquid mix module. For example, the dry additives and liquid fat aremixed for about 5 minutes to about 60 minutes, and optionally for about10 minutes to about 30 minutes, e.g., 15-25 minutes, at a temperaturesufficient to maintain the flowability of the liquid fat.

Minor liquid additives may also be mixed with the dry additives andliquid fat in the dry-liquid mix module, so long as the liquid additivesdo not detrimentally impact the desired efficacy of the dry additives.Conversely, dry additives may also be added in either dry form, or inthe form of a minor liquid mixture, to the liquid-liquid mix module,provided that those dry additives are suitably soluble in the major orminor liquid additive. Typical minor liquid additives include, forexample, vitamins, antioxidants, oils, dyes, colorants, and the like. Inone option, aqueous or fat immiscible liquid additives are added in theliquid mix module due to the rise in viscosity associated with mixingfat and fat immiscible or aqueous liquids together.

The resulting liquid fat-dry additive composition containing the liquidfat and dry additives (and optionally minor liquid additives) isintroduced into the liquid mix module where the dry additives are keptin suspension in the liquid fat. The liquid mix module preferablyconsists of mixing manifold, inlets for all fluids (liquid fat-dryadditive composition, liquid digest, and all other liquids) enteringinto the manifold, a liquid-liquid mixing device, preferably a closedand pressurized blender system, and one outlet for the overall surfacecoating composition. Mixing manifolds and blenders are well known in theart and the inventive process is not dependent upon the choice ofequipment used to carry out the process. Suitable mixing manifoldsinclude, for example, those manufactured by Silverson Machines, Inc.(East Longmeadow, Mass.), i.e., Silverson Model L150 or L200.

In the liquid mix module, liquid additives such as, for example, liquiddigest, oil, enzymes, acidulents, and the like, are mixed with theliquid fat-dry additive composition of the dry-mix module in the liquidmix manifold. At this stage, the dry additives should be sufficientlyencapsulated or surrounded by the liquid fat so as to protect thestability and sensitivity of the dry additives in the presence of thedamaging liquids. The temperature of the liquid mix manifold issufficient to maintain the flowability of the fat carrier and ispreferably the same temperature as maintained in the dry-liquid mixer.The residence time of the liquid fat-dry additive composition and theliquid additives together in the mixing manifold should be sufficient tointroduce the liquid additives to the liquid fat-dry additivecomposition.

The liquid exiting the liquid mix manifold containing liquid fat, dryadditives, and liquid additives is introduced into a mixer to mix theliquid fat-dry additive composition and liquid additives together, forexample, just prior to the enrobing or coating process. The liquidfat-dry additive composition and liquid additives may be mixed by anyconventional means for mixing, blending, or stirring compositionscontaining suspended solids. However, blending in a high shear mixer ispreferred because the resulting viscosity of the surface coatingcomposition is highly viscous.

When aqueous or fat immiscible liquid additives, e.g., liquid digest,are mixed with the liquid fat-dry additive composition, the viscosity ofthe resulting mixture increases substantially. However, it is notdesirable to reduce the viscosity by heating the mixture substantiallybeyond the melting temperature of the fat because of high processingcosts and safety concerns. In addition, heating the surface coatingcomposition at elevated temperatures will adversely impact both theflavor and nutritional value of the dry and liquid additives. Forexample, vitamins are known to substantially degrade upon exposure toheat. Probiotic micro-organisms are also sensitive to heat. Theresidence time of the composition in the blending device is sufficientto blend the composition before the viscosity substantially increases.In one option, the residence time of the composition in the blendingdevice is from about 1 to about 30 minutes, in another option, about 5to about 15 minutes, and in yet another option, about 8 to about 12minutes. E.g., 10 minutes.

Practitioners of the method will find it advantageous to position theliquid mix module close to the enrobing device for surface coating thedried animal food. Furthermore, the modules are positioned along thesame processing line, as opposed to producing the material in “batches.”The close proximity of the liquid mix module and the enrobing devicereduces the residence time of the surface coating composition in thepipes and pumps communicatively connecting the liquid mix module to theenrobing device, thereby avoiding the risk that the surface coatingcomposition will turn substantially viscous thereby rendering the pumpsuseless.

EXAMPLES

Lactobacillus and Bifidobacteria were provided to the surface of petfood kibble at a concentration of 10⁶ viable organisms per milliliter ofcoating composition. Briefly, microbes were provided as freeze-driedcultures to provide the dry material for mixing with liquid fat in thedry-liquid fat mixing module. Following the in-line mixing in the IKAmedium/high shear mixer, the dry-liquid fat mixture was transportedin-line to the mixing manifold, where it was combined with liquid digestApplied Food Biotechnology, Inc. (Fenton, Mo.). The dry-liquidfat-liquid digest combination was then transported in-line to ahigh-shear Silverson mixer (Silverson Machines, Inc., East Longmeadow,Mass.) for thorough admixing prior to application to the surface of thekibble. The Silverson mixer is positioned in close proximity to theenrober.

The method has also provided the tartar control agent sodiumhexametaphosphate, which is known to exhibit significant viscosity whencombined with liquid, to the surface of the kibble with even applicationat a concentration of approximately 0.4% by weight. Sodiumhexametaphosphate was provided as the dry ingredient to be admixed withliquid fat. Upon admixing the sodium hexametaphosphate in the IKA mixer,the mixture was transported to the mixing manifold to be combined withliquid digest supplied by Applied Food Biotechnology. This combinationwas then transported to the Silverson high-shear liquid mixer, where itwas thoroughly admixed prior to surface application to the kibble.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention. Ofcourse, variations of those preferred embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventors expect skilled artisans to employ suchvariations as appropriate, and the inventors intend for the invention tobe practiced otherwise than as specifically described herein.Accordingly, this invention includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by theinvention unless otherwise indicated herein or otherwise clearlycontradicted by context.

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this written document conflicts with any meaningor definition of the term in a document incorporated by reference, themeaning or definition assigned to the term in this written documentshall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. An apparatus comprising: a food processing line having at least onedry additive source comprising at least one of an antibiotic, aprebiotic, a Probiotic, a vitamin, an antioxidant, a carotenoid, and anenzyme, and at least one liquid fat source coupled with a first meteringsystem for supplying a predetermined amount of liquid fat in the foodprocessing line; the dry additive source and the liquid fat sourcecommunicatively coupled with a dry-liquid mixing device coupled with thefood processing line; a coating apparatus and a liquid-liquid mixingdevice communicatively coupled with the food processing line at a pointof delivery to the coating apparatus; and a liquid additive sourcecomprising at least one of a vitamin, an antioxidant, an oil, a dye, anda colorant, communicatively coupled with the liquid-liquid by a secondmetering system for supplying a predetermined amount of liquid additivein the food processing line.
 2. The apparatus as recited in claim 1,wherein the liquid-liquid mixing device is disposed in close proximityto the coating apparatus.
 3. The apparatus as recited in claim 1,wherein the coating apparatus comprises an enrober, wherein the foodprocessing line has a first end and a second end, the enrober isdisposed at the second end, and the liquid-liquid mixing device isdisposed adjacent to the enrober.
 4. The apparatus as recited in claim1, further comprising a pump coupled with the food processing linebetween the dry-liquid mixing device and the liquid-liquid mixingdevice.